| //The following program was coded by David Consiglio, Jr.
#include <iostream>
#include <conio.h>
#include <string>
#include <fstream>
#include <sstream>
#include <algorithm>
using namespace std;
string cand = "";
string max_cand = "";
int inc_pos = 0;
int first_pos = 0;
int sum = 101;
int test_sum = 0;
int counter = 1;
int e_pos = 0;
fstream out1;
int inc(int pos)
{
cand[pos]++;
cand[pos+1]--;
}
int generate()
{
int a = sum/9;
int b = sum % 9;
cand += char(b+48);
for(int q = 0; q < a; q++)
{
cand += '9';
}
max_cand = cand;
max_cand[max_cand.length()-1] = cand[0];
max_cand[0] = '9';
}
int locate()
{
for(int a = 0; a < cand.length()-1; a++)
{
if(cand[a] != '9')
{
inc_pos = a;
//cout << inc_pos << " ";
}
}
}
int rev_loc()
{
for(int a = cand.length()-2; a >= 0; a--)//search backwards for first non-9
{
if(cand[a] != '9')
{
first_pos = a;
a = 0;
//cout << "reverting to: " << first_pos << " ";
}
}
}
int main()
{
int steps = 0;
bool step_flag = true;
cout << "Palindromic Prime? ";
cin >> sum;
out1.open("candidates.txt", ios::out);
cout << "Display each ___ candidates. (0 for none, 1 for all, 10 for every 10th, etc.)" << endl;
cout << "Warning: Selecting 1 will result in slow execution for certain large primes." << endl;
cin >> steps;
if(steps == 0)
{
step_flag = false;
}
generate(); //determines lowest and highest candidates
cout << counter << " " << cand << endl;
out1 << cand << endl;
cand[0]++; //increment to 2nd lowest candidate (special case)
cand[1]--;
counter++;
if(steps == 1)
{
cout << counter << " " << cand << endl;
}
out1 << cand << endl;
while(cand < max_cand)
{
while(cand[cand.length()-1] == '9')//we are iterating through a run of 89 swaps
{
locate();
inc(inc_pos);
counter++;
if(step_flag && counter % steps == 0)
{
cout << counter << " " << cand << endl;
}
out1 << cand << endl;
}
rev_loc(); //undo all of the swaps
cand[first_pos]++; //increase the last non-9 number
cand[first_pos+1] = cand[cand.length()-1]; //put the last digit
cand[first_pos+1]--;
if(first_pos+1 != cand.length()-1)
{
cand[cand.length()-1] = '9'; //put the last 9 back
}
counter++;
if(step_flag && counter % steps == 0)
{
cout << counter << " " << cand << endl;
}
out1 << cand << endl;
test_sum = 0;
}
out1.close();
cout << "Finished at: " << counter << " " << cand << endl;
_getch();
}
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